The present invention relates to novel methods of making alkaline electric storage batteries and to novel electrode structures therefor.
The conventional method of making an alkaline storage battery, for example having a nickel positive and a cadmium negative is to form a perforated steel sheet having perforations 0.008 to 0.010 inches in diameter into a narrow channel section, a briquette of positive or negative active material made by compressing the active material powder is then inserted into the channel and a further sheet of perforated steel placed over the assembly and crimped round the edge of the assembly to close it. The channel strip is then cut to length and joined side by side to other strips to build up the necessary cell size. The assembly is then welded into a steel mesh container and current collectors attached.
This is a multistep process and it would be desirable if it could be simplified. In addition the use of dry powders introduces considerable handling problems.
We have discovered that these problems can be considerably reduced by introducing the active material into modified and novel forms of the plates by a novel technique. These plates are enveloped plate preferably tubular plates.
Tubular plates can have a variety of different types of porous tube material and tube configurations and can have tubes joined together or formed as separate tubes which are separately located on the current collecting elements of the cell.
One example of such separate tube arrangements utilizes woven fabric tubes having a thin outer plastic sheath provided with perforations about 1 to 2 mm. across spaced apart by about 1 to 2 mms. The plastic sheath is about 0.1 to 0.2 mms thick.